Casing protector



June 21, w L BETT|S I CASING PROTECTOR Filed March 3, 1928 1 INVENTOR; v WL'ZZZ'M I. .Bettz's, I

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Patented June 21, 1932 WILLIAM I. BETTIS, OF LOS ANGELES, CALIFORNIA I CASING PROTECTOR Application filed March 3,

In this specification, and the accompanying drawing, I shall describe and show a pre ferred form of my invention, and specifically mention certain of its more important objects. I do not limit myself to the forms disclosed, slnce various changes and adaptations may be made therein without departing from the essence of my invention as hereinafter claimed; and objects and advantages, other than those specifically mentioned, are included within its scope.

My invention relates to the protection of deep well casings and the like, and its principal ob ects are; first,vto provide improved means for keeping the members of a tool string or pump rod from rubbing against the Walls of the casing and causing abrasion thereby; second, to supply a casing protector that is adapted for greatly lessening the shocks of contact between the operating members and the casing; and, third, to supply a very simple, efi'ective, and relatively inex ensive device for these purposes.

y objects are attained in the manner illustrated in the accompanying drawing, in which- Figure 1 is a section of a deep well and casing, in which there is a tool string equipped with my improved protectors, the latter being shown in section;

Figure 2 is a side elevation of one of the protectors on a much larger scale, and with the top portion broken away to disclose the interior construction; and

Figure 3 is a plan view of this protector with a portion similarly broken away forthe same purpose.

Similar reference numerals refer to similar parts throughout the several views.

In the case of deep wells, it is impossible to keep tool strings or pump rods centered in the casing throughout its length. The rubbing of such parts against the walls of the casing, especially in the presence of a gritty uid, may easily result in wearing holes through the casin and in ruining parts of the tool string. t has been found that the use of rubberrings of sufficiently largeexte'rnal. diameter, distributed along the tool string, is quite satisfactory so far as prevent- 1928. Serial No. 258,988.

ing abrasion is concerned, since water is an excellent lubricant for rubber and is nearly always present in deep well drilling or operation. Such protectors were disclosed in United States Patent No. 1,573,031, issued 55. February 16, 1926, to myself and Leroy H. Perry jointly. Rubber rings thus used do not retain abrasive grit, by reason of their wet and slippery surfaces, and do not damage the casing by rubbing against it.

The chief difficulty that has been experienced in the use of such rubber rings has been to retain them in the desired positions on the tool string. 'Among the most practical means that has been devised for this purpose thus far, is to stretch the rings over the tool string members, and to depend upon their resilient gripping of these members in consequence. Such an arrangement is disclosed in the patent referred to above. It is quite 7o satisfactory at the start, but eventually the rings are liable to become loose and to be displaced.

It does not appear. to have been generally recognized, or at least the fact seems to have been largely overlooked, that rubber reallyisalmost incompressible. That is to say, if it is confined, its volume can be reduced only very slightly by pressure. On the other hand, of course, it is very easily distorted.

Under pressure the rubber will take a different shape, but its volume will remain almost constant.

The transverse pressure that the rubber rings descr'bed above receive by reason of their continual contacts with the walls of the well casing, causes the rubber to, distort in a direction that is perpendicular to the direction of pressure, since this is the only way that it can yield. The blows of the contacts cause the rubber to distort in'a direction that v is tangential to the circumference of the tool string, and tends to stretch the periphery of the ring, and to loosen its grip. I have discovered that, by the use of properly proportioned and' positioned recesses on the inner'sulrfaces of the rings, external pressure will make the material distort into the recess spaces and, as a consequence, the tendency to stretch is greatly reduced. Moreover, such recesses have the ability to act in the manner of vacuum cups, and in this way to assist materially in maintaining the rings in place.

I have fully utilized both of these principles in my present improved construction. My present invention comprises short tubular rings 5, of fairly soft and very resilient rubher, having rounded external shoulders 6 to prevent catching, when the tool string is being withdrawn from the well. The outer surfaces of these rings are smooth, toprovide the greatest possible amount of material for Wear. There is no wear upon the inner sur faces, and they are therefore provided without any detriment with a large number of recesses 7, in staggered arrangement as shown. The internal diameter of these rings, when not in place, is much smaller than the diameter of the parts 8 of" the tool string upon,which they are to beseated. Their outer diameter, when in place on the tool string, isconsiderably greater than that of the tool string parts to be protected, such as the couplings 9 or the tool joints 10. These rings, when stretched over the tool string members, grip them very tightly; and such gripping will be maintained for long periods of time by reason of the fact that the recesses 7 provide space for the rubber to distort into, w en it is subjected to transverse pressure by the contacts with the well casing.

I particularly desire to call attention tothe fact that the outersurfaces of these'improved protectors provide the maximum amount of material possible for resistin wear, since they are smooth and without deformations; and that the recesses in the inner surfaces not only serve to greatly prolong the effective ring of resilient material,- adapted for being stretched over a member of a tool string and thereafter to grip said member; the radial thickness of said ring being such that, when it is in place on said member, its outer diameter willibe greater than that of adjacent members of the tool string; and the interior surface of said ring being provided with a plurality of recesses.

3. A well casing protector comprising a ring of rubber, adapted for being stretched over a member of a tool string and thereafter to grip said member; the radial thickness of said ring being such that, when it is in place on said member, its outer diameter will be greater than that of adjacent members of the tool string; and the interior surface of said with a multiplicity of ring being provided adapted recesses in staggered arrangement,

to act as vacuum cups.

4. A protector comprising a ring of resilient material adapted to be stretched over and thereby to grip another member; the inner surface of the ringbeing recessed in such maner as to permit of its material being distorted into the recess space when it is externally compressed.

5. A protector comprising a ring of resilient material adapted to be stretched over and thereby to grip another member; the outer surface of the ring being smooth to provide the maximum of wearing surface; and the inner surface of the ring having circumferentially arranged recesses adapted for permitting its material to be distorted into the recess spaces when the ring is externally compressed.

6. A protector comprising a ring of protecting material resiliently gripping a member' of a'tool-string; the interior surface of said ring being recessed.

7. A protector comprising a ring ofresilient material gripping a member of a toolstring; the interior surface of said ring being recessed.

WILLIAM I. BETTIS. 

